Reactive oxygen species (ROS) play an important role in alcohol-induced organ and tissue damage. ROS oxidize DNA, proteins, lipids, and small molecules. Carbonylation is one mode of protein oxidation that occurs in response to iron-catalyzed, hydrogen peroxide (H2O2)-dependent oxidation of amino acid side chains. Although carbonylated proteins are generally believed to be eliminated through proteasome- dependent degradation, my laboratory discovered the protein de-carbonylation mechanism, in which formed carbonyl groups are chemically eliminated without proteins being degraded. Major amino acid residues that are susceptible to carbonylation include proline and arginine, both of which get oxidized to become glutamyl semialdehyde that contains a carbonyl group. Further oxidation of glutamyl semialdehyde produces glutamic acid. Thus, I hypothesize that, through the ROS-mediated formation of glutamyl semialdehyde, proline, arginine and glutamic acid residues within the protein structure may be interchangeable. In fact, our recent mass spectrometry results demonstrated that proline 45 (a well conserved residue within the catalytic sequence) of peroxiredoxin 6 molecule can be converted into glutamic acid in human cells, establishing a revolutionizing concept that iron-catalyzed oxidation elicits the amino acid conversion within the protein structure. The objective of this R03 project is to provide evidence for the occurrence of oxidant-mediated amino acid conversion, as a novel mechanism of alcohol-induced cellular damage. The objective of this application will be accomplished by pursuing two specific aims: 1) Identify the occurrence of amino acid conversions in in vivo and in vitro models of alcohol abuse; and 2) define the functions of amino acid conversion in relation to alcohol-induced cellular damage. The proposed work is highly innovative because it will address a revolutionizing concept that site-directed mutagenesis/protein engineering-like events occur naturally. Results will be significant because they are expected to provide a new molecular mechanism through which alcohol causes organ and tissue damage and help develop strategies to prevent and/or treat alcohol-related disorders.